//
//  Copyright 2012, Xamarin Inc.
//
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
//
//        http://www.apache.org/licenses/LICENSE-2.0
//
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//
using EmployeeDirectory.Core.Data;
using EmployeeDirectory.Core.Utilities;
using System.Reflection;
using System.Text.RegularExpressions;

namespace EmployeeDirectory.Core.Services;

public class MemoryDirectoryService : IDirectoryService
{
    List<Person> people;

    Dictionary<string, PropertyInfo> properties;

    public MemoryDirectoryService(IEnumerable<Person> people)
    {
        this.people = people.ToList();
        this.properties = typeof(Person).GetRuntimeProperties().ToDictionary(p => p.Name);
    }

    #region IDirectoryService implementation

    public void Dispose()
    {
    }

    public Task LoginAsync(string username, string password, CancellationToken cancellationToken)
    {
        return Task.Factory.StartNew(() =>
        {
            //Just for testing
            //HACK: Thread.Sleep (2000);
        });
    }

    public Task<IList<Person>> SearchAsync(Filter filter, int sizeLimit, CancellationToken cancellationToken)
    {
        return Task.Factory.StartNew(() =>
        {
            var s = Search(filter);
            var list = s.ToList();
            return (IList<Person>)list;
        }, cancellationToken);
    }

    IEnumerable<Person> Search(Filter filter)
    {
        if (filter is OrFilter)
        {
            var f = (OrFilter)filter;
            var r = Enumerable.Empty<Person>();
            foreach (var sf in f.Filters)
            {
                r = r.Concat(Search(sf));
            }
            return r.Distinct();
        }
        else if (filter is AndFilter)
        {
            throw new NotImplementedException();
        }
        else if (filter is NotFilter)
        {
            throw new NotImplementedException();
        }
        else if (filter is EqualsFilter)
        {
            var f = (EqualsFilter)filter;
            var upper = f.Value.ToUpperInvariant();
            var prop = properties[f.PropertyName];
            var q = from p in people
                    let v = prop.GetValue(p, null)
                    where v != null && v.ToString().ToUpperInvariant() == upper
                    select p;
            return q;
        }
        else if (filter is ContainsFilter)
        {
            var f = (ContainsFilter)filter;
            var re = new Regex(Regex.Escape(f.Value).Replace("\\ ", "|"), RegexOptions.IgnoreCase);
            var prop = properties[f.PropertyName];
            var q = from p in people
                    let v = prop.GetValue(p, null)
                    where v != null && re.IsMatch(v.ToString())
                    select p;
            return q;
        }
        else
        {
            throw new NotSupportedException("Unsupported filter type: " + filter.GetType());
        }
    }

    #endregion

    #region File IO

    public async static Task<MemoryDirectoryService> FromCsv(string path)
    {
        using var stream = await FileSystem.OpenAppPackageFileAsync(path);
        using var reader = new StreamReader(stream);
        return FromCsv(reader);
    }

    public static MemoryDirectoryService FromCsv(TextReader textReader)
    {
        var reader = new CsvReader<Person>(textReader);
        return new MemoryDirectoryService(reader.ReadAll());
    }

    #endregion
}
